This invention relates generally to abrasive blasting and more particularly to a mechanism for cleaning debris from confined areas.
Heavy industry requires the transportation of countless different chemicals, paints, petroleum products, and other liquids. The containers used for this transportation build up residue which must be periodically removed.
Into this application has come abrasive blasting, either sand blasting or its newer cousin, plastic media blasting. Both are very useful for cleaning containers. Typically the residue is less dense then the container substrate and a thorough cleaning can be easily and quickly performed. In using abrasive blasting, an operator typically enters the container (e.g. a railroad tank car or semi-truck tanker) and proceeds to remove the residue.
Within this discussion, the abrasive used is plastic media which is under moderate pressure to abrade unwanted material from the substrate. Those of ordinary skill in the art readily recognize that the present invention is equally applicable to other pressurized abrasive techniques, irregardless of the type of abrasive media used, and is not limited to, plastic, sand, and water blasting.
Because of the close confines of the container, two considerations play an important role in utilizing abrasive blasting for the cleaning:
(i) Ventilation--Requires that proper air flow be established to remove air-suspended dust so that an operator can see the substrate being cleaned; and, PA1 (ii) Media Recovery--The removal of used abrasive and debris in an organized manner.
To this end, one set of developments have sought to design specialty blast rooms. Examples of such rooms are described in: U.S. Pat. No. 2,912,918, entitled "Blast Room with Uniform Down-Draft Ventilation" issued to Mead on Nov. 17, 1959; U.S. Pat. No. 4,297,940, entitled "Protective Workplace and System" issued to Hainline on Nov. 3, 1981; and U.S. Pat. No. 3,863,392, entitled "Sand Blast Room" issued to Haker on Feb. 4, 1975. All of these references are incorporated hereinto by reference.
In all of these applications, the media recovery systems are outside the container and therefore unusable.
Because there is a lack of devices to address these problems, many operators of abrasive blasting systems for containers manually sweep up the media and shovel the media into buckets for removal from the container through the top opening. The buckets are then deposited into a standard media recovery hopper.
It is clear that this approach is both inefficient and time consuming.
Ventilation for a container abrasive blasting situation is usually accomplished by attaching the standard air cleaning system as described in several of the above referenced patents to an existing exhaust port located at the top of the container. In this manner, air is pulled through a top portal into the container and then through the exhaust port at the top of the container.
This arrangement completely ignores the media recovery problems discussed earlier.
Recovery of debris and media within a container poses difficult problems because of size considerations. These problems are magnified when debris must be cleaned from hoses (usually two to three inches in diameter) which are used to drain these containers.
The current state-of-the art approach to this problem is to soak the hoses in solvents and flush. The use of solvents poses a significant amount of environmental problems. Because of the cost of the solvents and associated problems in the disposal of the solvent/debris mixture, often these hoses are simply discarded.
The discarding of hoses is expensive.
It is clear from the foregoing that an efficient mechanism for the cleaning of hoses and the recovery of media does not exist.